Orthogonal frequency division multiple access (OFDMA) allows for multiple users to share wireless resources of a wireless communications network in both frequency and time. A standard for OFDMA operation is according to IEEE (Institute of Electrical and Electronics Engineers) 802.16e. According to OFDMA, different users can be assigned different sets of subcarriers (at different frequencies), where the subcarriers are closely-spaced orthogonal subcarriers, with each subcarrier modulated with a modulation scheme. Each group of subcarriers assigned to a user is referred to as a subchannel.
According to OFDMA, a data region (also referred to as a data burst) that is to be communicated across the forward or downlink wireless link between a base station and a mobile station is provided with a two-dimensional allocation of a group of contiguous subchannels (frequency axis) within a group of contiguous OFDMA symbols (time axis). The allocated data region can be visualized as a rectangle, where the rectangle is made up of a number of subchannels in the subchannel axis (e.g., vertical axis) and a number of OFDMA symbols (e.g., horizontal axis).
An issue associated with allocation of OFDMA resources (including OFDMA symbols and subchannels) is that there is limited flexibility in how OFDMA resources are allocated to data bursts associated with different users in rectangular regions in frequency and time.